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Fracture rate in Turner syndrome comparable to healthy adolescent girls

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January 5, 2018

Ondrej Soucek
Ondrej Soucek

Girls with Turner syndrome treated with recombinant human growth hormone and estrogen therapy do not have an increased risk for fracture incidence vs. girls in a healthy population, according to findings from a 6-year prospective study.

“Based on our estimate of fracture incidence in healthy controls, the observed girls with Turner syndrome who sustained fractures during the 6-year follow-up was completely expectable,” Ondrej Soucek, MD, PhD, of the department of pediatrics at Charles University and Motol University Hospital in Prague, told Endocrine Today. “This finding was further supported by the fact that the calculated bone strength of the radius, as assessed by peripheral quantitative computerized tomography, was comparable to the reference, when the decreased body height of girls with Turner syndrome was taken into consideration.”

Soucek and colleagues analyzed data from 32 adolescent girls with Turner syndrome (confirmed with genetic testing) participating in a previously published study using peripheral quantitative CT. Within the cohort, 15 girls were prepubertal (Tanner stage I breast development), 14 were pubertal premenarcheal and three were postmenarcheal. Six girls developed spontaneous puberty; 24 girls with primary amenorrhea and two girls with secondary amenorrhea were treated with oral estradiol to induce puberty. All were treated with recombinant human GH at a median dose of 50 µg/kg per day; postmenarcheal girls finished their GH therapy less than 8 months before their first densitometry assessment. Girls underwent bone scans at baseline and 2, 4 and 6 years, with researchers measuring total bone mineral content, total bone cross-sectional area and trabecular volumetric bone mineral density and polar strength-strain index at the distal radius. Researchers assessed fracture incidence via questionnaires. For peripheral quantitative CT-derived bone parameters, researchers used age-specific reference values for bone density and geometry parameters from a control group of 185 healthy girls from the DONALD study in Germany. Primary outcome was fracture occurrence.

During 6 years of follow-up, three girls sustained four fractures, all from falls. Researchers determined that the fracture rate among girls with Turner syndrome was not higher than the downward-biased fracture rate estimate in the age-matched healthy controls (P = .48).

Among girls with Turner syndrome, trabecular BMD z score decreased with age (estimate, –0.21; P < .001); however, total bone CSA correspondingly increased (mean, 0.16; P < .001), which led to normal bone strength, according to researchers. A positive history of incident fractures was not associated with any bone parameters, they noted.

“Even though trabecular vBMD decreased during puberty, total bone [cross-sectional area] increased and led to normal calculated bone strength at the metaphysis of the radius, which supports the finding of a ‘common’ fracture rate in [Turner syndrome],” the researchers wrote.

“Despite that our study was not designed to evaluate the influence of the treatment, we believe that the current standard of care (growth hormone and estrogens) might be the crucial factor ‘normalizing’ the bone phenotype in Turner syndrome,” Soucek said. “Our deduction is based on the finding that the longer the growth hormone treatment, the higher the cortical bone mineral density at the diaphysis of the radius. This can be seen as another reason for appropriate hormonal treatment in Turner syndrome.” – by Regina Schaffer

For more information:

Ondrej Soucek , MD, PhD, can be reached at Charles University and Motol University Hospital, Department of Pediatrics, Second Faculty of Medicine, V Uvalu 84, 15006, Prague, Czech Republic; email: ondrej.soucek@lfmotol.cuni.cz.

Disclosures: The authors report no relevant financial disclosures.